This project considers how to design emerging Mixed Reality technologies (including AR and VR) so that they are usable by and useful to people of all abilities. Too often, the accessibility of technology to people with disabilities is an afterthought (if it is considered at all); post-hoc or third-party patches to accessibility, while better than no solution, are less optimal than interface designs that consider ability-based concerns from the start. Mixed Reality (MR) technologies are at a crucial point of near-maturity, with emerging, but not yet widespread, commercialization; as such, MR technologies have an opportunity to integrate accessibility as a fundamental, developing cross-industry standards and guidelines to ensure high-quality, inclusive experiences that could revolutionize the power and reach of this medium.